Electric switch



Filed Ila-y 31, 1947 J. M. DE MONTMOLLIN ETAL ELECTRIC SWITCH June 6, 1950 JAMES M. Dt'MO/YTMOL L IN 77/0/1445 5 CURTIS AGENT- Patented June 6, 1950 cmc'mro swrrcn James M. de Montmollin and Thomas E. Curtis, Hampton, Ga., assignors to Southern States Equipment Corporation,

Georgia a corporation of Application May 31, 1947, Serial No. 751,568 8 Claims. (Cl. 200-48) This patent relates to high voltage electric switches of the type in which two contact-making terminals, relatively movable, are first brought into engagement with one another and then the pressures between the terminals are greatly increased by continued relative movement between these said members.

One purpose is to provide a. switch of this type in which a relatively slight movement of the terminals develops the desired minimum high pressure, another purpose is to limit this pressure to a predetermined maximum while permitting considerable variations of members and movement. Another purpose is to provide a compact, and durable pre-stressed spring which will maintain the desired high pressures over a considerable range of travel, and which can be readily adjusted to obtain proper coordination of the pressure members for each individual switch unit. Another purpose is to provide contact members which all have high conductivity. Other pur poses will be evident from the specification and claims.

In the drawings, Figs. 1 and 2 show in small scale two views of a single pole switch unit of one design embodying this invention; Fig. 3 is a larger scale view of the terminals not fully closed; Fig. 4 is plan view of terminals when fully closed; Fig. 5 is a side view of terminals when closed; and Fig. 6 is a cross section view on section 6-8.

A base I carries two bearings which support the two rotatable insulator units 2, 2, and these are interconnected by the rod 4. The crank I is the means for rotating both insulator units simultaneously in opposite directions. Line connections B, l are pivotally secured to units 2, 3, respectively; and arms 8, 9 are solidly secured to insulator units 2, 3 respectively.

Arm 8 carries terminal II), which is preferably a single conducting forked member secured to arm 8 by bolt The tips of the tines, l2, l3, are flared and they act as guides, the ribs l5, l5 and the webs l6, l6 stiffen the fork, and the two sides of the fork have contact surfaces l1, I! which aresubstantially parallel and these sides may be silvered or otherwise finished as desired.

Arm 8 carries a terminal assembly I! made of two similar members which are clamped to arm 9 by bolts and nuts |9--|9. The flat bar portions 20, have enough flexibility to allow the small area, high pressure contacts 2|, 2| to be expanded or contracted without producing improper strains.

as guides as the terminals are becoming engaged. The webs 22, 22 and 22, 23 together with the The tapered tips 2|, 2| act covers 24 and 25 enclose the space where the spring 28 is housed. Bolt 21 and nuts 22, 22 are used to compress spring 2' to exert the desired minimum high pressure against the two members of it. One or more washers 30, may be inserted or removed as desired so that the contacts 2|, 2| are properly spaced when spring 2 l is compressed to give this desired tension.

The spacing between 2|, 2| is such that the assembled terminal I! is readily inserted between surfaces l1, I! when terminals I0, I. are at an angle as shown in Fig. 3; and yet when arms 8, 9 have been brought into alignment as shown in Figs. 2 and 4, then the contacts 2|, 2| have been compressed slightly thereby removing all stress from bolt 21 and nuts 28, 29 so that the full stress of spring 28 is exerted in opposite directions to produce equal pressure between contacts 2|, 2| and their respective surfaces H, II.

Operation is as follows:

Assume that the switch is open and the arms 8, 8 are in the positions shown by dotted lines in Fig. 2. The longitudinal axes of the two arms are in the same operating plane but they are at angular positions to one another. Both tines of the fork l0 and the two contacts 2|, 2| all move in this same operating plane and so a closing motion of crank 5 will bring the arms together until fork l0 and the terminal assembly I! engage as shown in Fig. 3, with the two contacts 2|, 2| in an angular position between the sides I1, l1. Further closing motion brings the longitudinal axes of the two arms 8, 9 substantially into alignment as shown in full lines: in Fig. 2, and the contact members come into the positions shown in Fig. 4.

The contacts 2|, 2| have thereby been squeezed together by faces IT, I! with a scraping action which removes dirt and scale from all contact surfaces, and the heavy pressure from spring 28 ensures high conductivity contacts everywhere. A compression motion of a few hundredths of an inch is enough to transfer the pressure of spring 28 from bolt 21 to surfaces I1. And a coil spring such as 26, which is already compressed to exert a pressure of say 200 pounds, can be compressed another sixteenth'of an inch or more without developing more than say 250 pounds of pressure. Thus, the spring 28 which is prestressed to give the minimum desired pressure, can readily be compressed as much more as may be required by irregularities of individual switch units, without developing such heavy pressures that the parts can be operated only with great difliculty.

There is the same conductivity in all similar members. the current flow is thereby divided into twosimilarpathaandsotheheatingeifectis low.

'Ihisinventioncanbeusedinaswitchinwhich the two switch arms are of different lengths; either terminal with its supporting arm may be made as a single member instead of being an assembled structure; the switch arms may be mounted and operated in various ways, so long as they can be given the required movement relative to one another; the contacts II. II may be disposed in a plane that is not necessarily normal to the length of arm I; and other changes can be made by one familiar with the art without departing from the spirit and purposes of this invention.

We claim:

1. In an electric switch, two relatively movable conductor terminals pivotally mounted in spaced relationship and cooperable to swing into and out of engagement with one another one of said terminals being a rigid fork, the second terminal comprising two similar elongated conducting members clamped together at one end and with a pair-of expansible and compressible high pressure contacts at their other end, a coil spring to bias the pair of contacts towards expansion and stop means to limit said expansion, integral parts of the said two elongated conducting members also forming a protective enclosure tohouse said coil spring.

2. In an electric switch, two spaced insulated supports, a terminal conductor in the form of a rigid fork movably supported by one of said supports, and movably supported on the other of said supports a second terminal comprising two spaced contacts biased apart from one another and with their separation limited by a stop, both tines of the said fork and the said two spaced contacts being swingable in the same operating plane with one another, together with operating means for positioning the said secondterminal freely between the sides of said fork and thereafter for moving said second terminal and the said fork angularly with respect to one another to force said two spaced contacts more closely together.

3. In an electric switch, a conducting terminal in the form of a rigid fork, a second terminal .comprising two spaced contacts and a spring biasing said contacts apart and a stop to limit the separation of said contacts, the normal width of ,said second terminal being greater than the space between the sides of said rigid fork, both tines of the fork and the said two spaced contacts all being swingable in the same operating plane with one another, together with means operative by one continuous motion to move said two contacts freely into the space between the sides of said fork and thereafter to move the said two contacts angularly with respect to said fork and thereby to force said two contacts more closely together.

4. In an electric switch, a pair of spaced insulators, a pair of switch arms each with a terminal on its swing end, said switch arms being supported by said insulators and being rotatable simultaneously about their respective axes to bring said terminals into mutual engagement, one

between the sides of said fork that. said contacts enter freely into the space between the side of said fork as the terminals begin their mutual engagement but by the continued rotation of said switch arms the said contact surfaces are forced more closely together by pressure against the sides of said fork.

5. In an electric switch, two swingably mounted conducting terminals cooperable to open or in close the switch. one of said terminals being a fork with a fixed space between the substantially parallel sides of the fork, the other of said terminals including two relatively movable contacts normally spaced to a width greater than the said fixed space between the sides of the fork, both tines of the fork and the said two spaced contacts being swingable in the same operating plane with one another, together with means operative to swing the said two contacts freely and in a position angular to the longitudinal axis of the fork into the said space between the sides of the fork,

and thereafter to move the said two contacts within the said fork into a position transverse to the longitudinal axis of the fork and thereby to force the two contacts more closely together.

8. In an electric switch, a pair of cooperable switch arms mounted for rotation. respectively, about two spaced parallel axes, a rigid fork as a terminal on the swing end of one of said arms, a terminal assembly on the swing end of the other said arm and engageable with said fork, the said terminal assembly including a Pair of high pressure contacts which form a transverse compressible head with a normal width greater than the space between the two sides of said fork, both tines of the fork moving in the same operating plane as that in which the two arms swing, together with means operative to rotate simultaneously the two arms about their respective axes and thereby to position the compressible head freely in an angular position within the space between the sides of the said fork, and thereafter by continued rotation of the arms to bring the head into a position transverse to the longitudinal axis of the fork thereby to compress the said head.

7. In an electric switch, a pair of cooperable switch arms mounted for rotation, respectively, in the same operating plane, about two spaced parallel axes, a rigid fork as a terminal on the swing end of one of said arms, both tines of said fork being in the said operating plane, a terminal assembly on the swing end of the other said am and engageable with said fork, the said terminal assembly including a pair of high pressure contacts which form a transverse compressible head with a normal width greater than the space between the two sides of said fork, together with means operative to rotate simultaneously the two arms about their respective axes and thereby to position the compressible head freely in an angular position within the space between the sides of the said fork, and thereafter by continued rotation of the arms to bring the longitudinal axes of the said two arms into alignment.

8. In an electric switch a pair of cooperable switch arms each rotatable about its own axis and both arms rotating in the same operating James M. n: ubmoum. moms 1-; 0mm.

6 mmnumcss crrnn The following references are of record in th file of. this patent:

Number Number 843,542

UNITED STATES PATENTS Name Date French et a1. Jan. 15, 1924 Croft Dec. 8, 1931 Koppitz Nov. 14, 1933 Koppitz Feb. 27, 1934 Ramsey Aug. 13, 1940 a Van Sickle et a1. Oct. 28, 1941 FOREIGN PATENTS Country Date Germany Apr. 10, 1937 

